As data storage systems become ever bigger, providing efficient backup storage becomes increasingly important. Backups can be used for a variety of purposes. They can be used to recover from user error when, for example, the user inadvertently deletes or overwrites a file. They can be used to recover from data loss due to hardware failure such as a hard disk failure. They can also be used to recover from software failures such as application or operating system crashes. The goal of recovery after a crash is to restore the last available known good operating state for the complete system. This can be done by rebooting the same hardware after restoring the file system from a suitable backup, but the recovery procedure can be very time-consuming if the entire file system must be restored. For this reason, virtual machines (VMs) are sometimes used for backup purposes. When a VM is used for backup purposes, it is typically not used as a running machine unless and until it is needed for restoring a failed machine. Typically, the VM is launched, booted, and tested only to verify functionality and then it is shut down; however, it can be brought back on-line quickly if and when needed to replace the failed source machine for which it is functioning as a backup.
As such, if a VM is used as a backup and the source machine goes down, the VM can be quickly powered on in its place. Whereas a full system restore from traditional backup methods can take hours, the VM can be up and running in a few minutes. Examples of commercial products that enable VMs to be used for backup include POWERCONVERT® from PLATESPIN®, Ltd., VEEAM BACKUP™ from Veeam Software, and VMWARE CONVERTER™ and P2VMOTION™ from VMware, Inc. The conversion from a source computing machine to a VM is commonly referred to as “P2V conversion” (physical-to-virtual conversion). Various implementations and features of the P2V conversion process are disclosed in U.S. patent application Ser. No. 12/197,768, filed on Aug. 25, 2008, U.S. patent application Ser. No. 12/616,902, filed on Nov. 12, 2009, and U.S. patent application Ser. No. 12/618,280, filed on Nov. 13, 2009. The entire contents of these three applications are incorporated by reference herein.
The full P2V conversion process for a source machine can take several hours, if not days. Because of this, the management of such conversions becomes very difficult in situations where there are a large number of source machines to be converted, e.g., in server farms, and/or there are only a limited number of days to complete the conversion. Other factors, such as the limited availability of personnel with the appropriate expertise to oversee the conversions, may further complicate the management of P2V conversions.